1. Field of the Invention
The present invention is generally related to flow measurement.
2. Description of the Related Art
Conventional methods for measuring intraluminal flow, such as blood flow, include use of continuous wave Doppler methods in which a transducer transmits an ultrasonic signal and another transducer receives echoes from the sound reflecting off of surfaces moving along with the fluid. These conventional systems are generally more responsive to a velocity component of the flow that is along a midline between the two transducers.
Conventional approaches include a first intraluminal transducer configuration 10, which positions a transmit transducer 12 and a receive transducer 14 on opposite sides of a lumen 16 (such as in an inner area of a blood vessel or other biological structure of a biological body) as shown in FIG. 1. With these conventional approaches the transmit transducer 12 and the receive transducer 14 are symmetrically aligned with a first fluid flow 18a and/or an oppositely directed second fluid flow 18b, which both collective are known herein as fluid flow 18. The transmit transducer 12 sends out a transmitted beam 19 that is reflected off of surfaces 20 traveling in the first fluid flow 18a and/or the second fluid flow 18b through a sampling region 22 as a reflected beam 24 to be received by the receive transducer 14.
Alignment of the transmit transducer 12 and the receive transducer 14 is such that the transmitted beam 19 and the reflected beam 24 are downstream of the transducers with respect to the first fluid flow 16 and upstream of the transducers with respect to the second fluid flow 18 as further shown in FIG. 1. By symmetrically positioning the transmit transducer 12 and the receive transducer 14 in the lumen, measurements can be responsive to a flow vector component that is coaxial with an overall longitudinal direction 26 of the lumen to increase sensitivity of the flow measurement.
Other conventional approaches include a second intraluminal transducer configuration 30 that positions the transmit transducer 12 and the receive transducer 14 on a same side of the lumen 16 as shown in FIG. 2. In implementations, the transmitted beam 19 and the reflected beam 24 are obliquely aimed to overlap into a version of the sampling region 22 that can have a trapezoidal shape.
Unfortunately, in at least some cases, space to position fluid flow measuring devices intraluminally is rather limited, which tends to restrict the number and/or quality of the device components used. Consequently, measurement accuracy of fluid flow may be less than desirable.